CppCon 2017: Michael Spencer “My Little Object File: How Linkers Implement C++”

[@echosystemd]

Best Q&A session in CppCon I've seen.

[@TheDonkeydash]

Omg this guy sounds exactly like linus tech tips

[@echosystemd]

Return value of step0 on Bash on Debian is not 24567837. It shows 29 instead (24567837 % 256 = 29).

[@aiman_yt]

echo I thought return value is an int, not a byte

[@ericcurtin2812]

Hmmm interesting he's probably using the Playstation OS itself which is based on FreeBSD, possibly a platform difference

[@ericcurtin2812]

Or maybe it's MacOS just saw his laptop! Also a FreeBSD derivative

[@Athenas_Realm_System]

@@ericcurtin2812 Mac is a BSD derivitive not FreeBSD, it came from earlier BSD through NeXTSTEP

[@andreyv116]

The mechanism that produces such high a number is unusual. Bash (and honestly, most shells) use waitpid and the WEXITSTATUS macro to get an 8-bit exit code

[@dawidskrodzki]

It starter well but then he went way to fast, both with the content of the talk and and his speech speed.

[@1Infinitive1]

What does he mean at 10:48? Why is that subtraction needed?

[@andersknatten]

It's because the instruction pointer is already pointing to the next instruction when this instruction gets executed. So the relative jump will be the distance from this location to wherever we want to jump to, minus four bytes to compensate for the instruction pointer already pointing four bytes into the future. It's explained in more detail at 13:56 in this talk: kzbin.info/www/bejne/nHjRk3qObZ2tabs (but if you watch from the beginning it's easier to understand).

[@homomorphic]

I started watching and the first slide does not even remotely reflect how linkers work in 2017 (this is cppcon2017).

[@pnadk]

Unfortunately he speaks so fast that I can not understand this talk.

[@max0x7ba]

pnadk He does. Turn on subtitles.

[@MsGrooveOn]

I stated to watch it using 1.2 speed and it was ok for me, lol

[@dennisorbison7318]

watch at half speed.

[@LostieTrekieTechie]

first